The dolphins probably left and their last message was misinterpreted as a surprisingly sophisticated attempt to do a double backward somersault through a hoop whilst whistling “The Star-Spangled Banner”, but in fact the message was this: “So Long, and Thanks for All the Fish.”
They are an advocacy group, they go where their audience is. Of you are looking for white dudes what’s the point of looking for them in the fediverse, where 98% of them already agree with you?